The eight Democrats disapprove of using the annual budget debate to pass Obama’s “cap and trade” bill to fight greenhouse gas emissions, a measure that divides lawmakers, environmentalists and businesses. The lawmakers’ opposition makes it more difficult for Democratic leaders to move the bill without a threat of a Republican filibuster.

The budget debate is the only way to circumvent Senate rules that allow a unified GOP to stop a bill through filibusters.

“Enactment of a cap-and-trade regime is likely to influence nearly every feature of the U.S. economy,” wrote the Democratic senators, mostly moderates. They were joined by 25 Republicans. “Legislation so far-reaching should be fully vetted and given appropriate time for debate.”

It takes 60 votes to overcome a filibuster in the Senate, but Democrats and allied independents currently control 58 seats.

Under a cap and trade system, the government would auction off permits to emit greenhouse gases such as carbon dioxide. The auctions would raise almost $650 billion over the next decade, with the cost passed on to consumers as higher energy prices.

The cap and trade proposal is highly controversial, especially in heavily industrialized states and regions where people get their electricity from coal-fired power plants. Obama’s promise to use most of the revenue to award $400 tax credits to most workers hasn’t quelled the controversy since the increases in utility bills could easily exceed the amount of the tax cut.

Fast-track budget rules were used to enact President George W. Bush’s tax cuts and two major budget bills during the Clinton administration, including a 1993 measure that failed to win a single GOP vote.

The House and Senate Budget committees are slated to vote on the budget resolution next week, with Senate debate scheduled for the week of March 30.

There also has been speculation that the expedited rules could be used to pass a health care overhaul bill, but senior Senate Democrats such as Finance Committee Chairman Max Baucus, D-Mont., oppose the idea, saying health reform must be enacted on a bipartisan basis.

The White House is open to the idea of using the fast-track rules for both global warming and health care.

“We would prefer not to start there, but we’re not taking anything off the table at this point,” White House budget chief Peter Orszag said last week.